Cellulose-acetate composition



Patented Sept. 6, 1927.

UNITED STATES ATENT OFFICE.

STEWART J. CARROLL, OI ROCHESTER, NEW YORK, ASSIGNOR TO EASTMA .N KODAK COMPANY, OE ROCHESTER, NEW YORK, A CORPOBATIOI; OE NEW YORK.

CELLULOSE-ACETATE COMPOSITION.

No Drawing.

This invention relates to cellulose acetate compositions of low inflam'mability- One baths, combine ow inflammability' with practical freedom from color and possess, in short, the desired pro erties of a support 1 for sensitive photograp ic coatings. Still another object of my invention is to produce a composition which may be used in film, varnish or plastic manufacturing without injury to or being injured b the substances with which it is associated urin manufacture, storage or use. Further o jects will hereinafter -appear..

I have found that cellulose acetate compositions having the desirable, qualities enu- 26 merated above can be obtained'by mixing -cellulose acetate, referably of the acetonesolublet pe',,witl 1 tionpro uct of'benzol and its homologue-s, especially those which are liquid at ordinary 30 like toluene, xylenes, mesitylene, ethyl benzene, cumene and cymene. In all cases the substitution product should be-substantially free from uncombined bromine and hydrobromic acid. Moreover, the composition should be effectively neutr'al,that is, containing an insufiicient concentration of acid to break down the. substitution product or liberate bromine from it. I prefer, at pressent, to use monobrombenzol, parabromotoluene and orthobromotoluene, but it will be understood that my invention is not restricted to these individual substances, except as indicated in the appended claim.

Compositions of cellulose acetate andsuch brom substitution products have a surprising degree of practical non-inflammability, that is, an unexpected slowin down of the propa ation of combustion t erein'. Films of suc compositions, when ignited, often go out and must be reignited several times during the test, the flame traveling along the film very slowly.

Unless certain precautions are taken, films a brom-nucleo substitutemperatures and have saturated side chains- Application filed April 27, 1825. Serial No. 26,808.

embodying such compositions may become dlscolored beyond the manufacturing tolerance wh ch is ermissible. The first precaution is to ree the brom substitution product from free bromine and free hydrobromic acid. The other precaution is to keep the mixture efi'ectively neutral-so that therewill be insuflicient ac d to split up the substltution products. I consider films resultmg from these recautions to be colorless when they fall wit 'in the customary manufacturing tolerances as regards color.

In one form of my invention I may, for example, dissolve 100 parts by weight of acetone-soluble cellulose acetate in 300 to 500 parts (say 400 parts) of acetone alon with 5 to 50 parts (say 30, parts) of mono rombenzol.

In another illustrative embodiment of my invention I may dissolve 100 parts by weight of cellulose acetate in 300 #0500 parts (say- 400 parts) of acetone along with 5 to 50 1 parts of parabromotoluene, 30 parts being typical. In lace of the parabromotoluene I may substitute from 5 to 40 parts of orthobromotoluene, 30 parts being typical.

The ingredients are mixed thorou hly to form a homogeneous solution or owable mass. which is filtered if desired. When more flowab'le solutions are desired, or when the compositions are to be employed as lacquers, the volatile solvent ma be increased, as will befunderstood y those skilled in' the art, or volatile non-solvents, such as benzol, alcohol, and the like may be added, but not to the point where precipitation' occurs. Along with the ingredients given in the above examples, I may'add one. or more organic bodies ofonly slight volatility which enhance the plasticity or flexibility of the com ositions, and regulate the preparation of 1m therefrom;" but such bodies are'not preferred or essential. Examples of them are amyl or butyl acetate,'the various amyl alcohols, the various butyl alcohols, andmixtures of them.

Films prepared from the hereinabove described compositions are flexible, smooth, transparent and suitable for photographic purposesQ Moreover, the .absence of free bromine and free hydrobromic acid initially and throughout the useful life of 1 the films, prevents injuryto any photographic coatings or discoloration of the com- 'substance which absorbs position. Of course, a small amount of a bromine (like dicyandiamine) and blends with the other ingredients of the film without injuring the photographic coatings may be incorporated in the compos'tions as an insurance against trouble, but this is unnecessary when the composition is prepared with reasonable care While observing the precautions hereinabove set forth.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

As an article of manufacture, a substantially colorless, transparent, flowed film of low inflammability, which is substantially inert toward photographic coatings, which. comprises acetone-soluble cellulose acetate and a substance selected from the group of monobrom benzols and monobrom toluenes,

which is substantially free from uncombined bromine and hydrobromic acid, said film being formed from a composition containing from 5 to 50 parts by weight of said substance for every 100 parts of said acetate.

Signed at Rochester, New York this 25th day of April, 1925.

. STEWART J. CARROLL. 

